A carbon carrier material with sodium dendrite growth alleviation, rich in microporous and closed pore structure, and a preparation method and application thereof

Abstract

The application discloses a carbon carrier material for relieving sodium dendrite growth, rich in micropores and closed pore structure, and a preparation method and application thereof, and belongs to the technical field of low-dimensional material energy storage devices. The preparation method comprises the following steps: SO1, cross-linking reaction of a phenol source, a cross-linking catalyst and a formaldehyde solution; SO2, obtaining an impurity-containing sample through a high-temperature carbonization reaction; and SO3, adding the impurity-containing sample into a solvent for soaking, suction filtration, washing and drying to obtain the carbon carrier material. The carbon carrier material prepared by the application is uniformly distributed, the selection and pore size of the pores are adjustable, can effectively provide rich sodium-philic sites for inducing uniform deposition of sodium, and can inhibit the dendrite growth of a sodium metal battery in a cycle process; the pores serve as three-dimensional Na + Transmission channels are beneficial to forming a good ion migration path, reducing the current density of a local material, reducing the possibility of forming dendrites, and improving the safety and service life of the energy storage device.

Description

Technical Field

[0001] This invention belongs to the field of low-dimensional material energy storage device technology, and in particular relates to a carbon carrier material with micropores and closed-pore structure that alleviates sodium dendrite growth, as well as its preparation method and application. Background Technology

[0002] Metal batteries have attracted widespread attention in the field of energy storage in recent years. Sodium metal batteries are similar to lithium metal batteries, but sodium metal batteries have a higher theoretical capacity (1166 mAh·g). -1 Sodium metal batteries, with their advantages of low electrode potential (-2.714V vs SHE) and high energy density, show broad application prospects in large-scale energy storage and portable electronic devices. Furthermore, their abundant raw material sources and low cost make sodium metal batteries a promising candidate to become a strong competitor to lithium batteries in the future. However, sodium metal batteries also face some technical challenges, some of which are listed below:

[0003] (1) Non-uniform Na deposition leads to uncontrolled growth of Na dendrites; (2) Side reactions between Na metal and organic liquid electrolyte result in the formation of an unstable solid electrolyte interphase (SEI) layer, leading to continuous consumption of electrolyte and Na metal; (3) The volume of Na changes significantly during electroplating / stripping; (4) The continuous growth of sodium dendrites can penetrate the separator, causing internal short circuits and thermal runaway in sodium metal batteries. All of these problems can lead to poor battery cycle stability and shorten battery life, causing safety hazards.

[0004] The most serious consequences are caused by the uncontrolled growth of sodium dendrites. The growth mechanism involves sodium ions migrating from the positive to the negative electrode during charging, resulting in sodium metal deposition on the negative electrode surface. However, sodium metal deposition is not uniform, especially at high current densities or rapid charge / discharge rates, where dendritic structures often form on the electrode surface. Currently, methods to address sodium dendrite growth can be broadly categorized as: ① introducing three-dimensional current collectors to reduce local current density; ② constructing artificial SEI films on the sodium metal surface; and ③ building sodium metal current collectors with high specific surface area and high sodium affinity.

[0005] Among them, constructing sodium metal current collectors provides a simple and effective strategy. The design and construction of such current collectors usually have the following characteristics: (i) high specific surface area, which can reduce local current density and provide more nucleation sites, and inhibit dendrite growth; (ii) by introducing sodium-loving functional groups, the deposition overpotential can be reduced, the deposition behavior of sodium can be improved, and the uniform deposition and growth of sodium metal can be promoted; (iii) the three-dimensional porous structure can buffer the impact of sodium metal volume changes during the cycling process.

[0006] Currently, the specific types of carbon-based materials for sodium metal batteries can be broadly categorized as follows: ① Graphite and graphene. Graphite, as a traditional anode material, possesses excellent electrical conductivity and reversibility. Its extremely high specific surface area, superior conductivity, and mechanical strength make it an ideal material for sodium metal battery anodes. Through compositing with sodium metal, graphene can improve the morphology of the anode, suppress dendrite growth, and enhance battery performance; ② Carbon nanotubes (CNTs) possess a one-dimensional nanostructure, providing more electrical conductivity channels, which helps improve the conductivity and sodium ion conduction speed of sodium metal batteries. Simultaneously, carbon nanotubes can also help stabilize the morphology of the sodium metal anode through their excellent mechanical properties, preventing electrode volume expansion; ③ Porous carbon materials (such as activated carbon and carbon aerogels) have a large specific surface area and can serve as supporting materials for sodium metal anodes, enhancing the sodium ion transport rate and improving battery capacity and cycle stability by increasing the reaction interface. Meanwhile, the porous structure can also mitigate volume changes during sodium metal deposition, thereby improving the mechanical stability of the battery; ④ Conductive polymers (such as polyaniline, polypyrrole, etc.) are often combined with carbon materials and used in the electrode materials of sodium metal batteries. These materials not only provide additional conductive pathways, but also improve the electrochemical stability of the electrode through interaction with sodium ions.

[0007] While carbon-based materials can suppress sodium dendrite growth to some extent, further research is needed to completely and effectively address this issue. Currently popular porous carbon materials possess both mesopores and micropores, which are open pores and serve only as defects to improve certain cycling stability. However, their effectiveness against sodium dendrites remains questionable. + Nucleophilicity is limited. Suitable closed-pore structures can effectively improve the sodium affinity of materials. Carbon materials with closed-pore structures derived from carefully designed polymers offer advantages such as a stable carbon skeleton and avoidance of environmental pollution from pretreatment before carbonization. Due to their unique physical and chemical properties, polymers can control the formation and pore size of pore structures by altering their degree of crosslinking, crosslinking network, and interaction forces. Furthermore, at higher degrees of crosslinking, the density of the polymer network increases, and the pores of the carbonized material will close due to network contraction, forming a closed-pore structure. Summary of the Invention

[0008] Based on this, embodiments of the present invention provide a carbon support material with a microporous, closed-pore structure that alleviates sodium dendrite growth, as well as its preparation method and application. The preparation method of the present invention uses low-cost phenolic resin as a raw material and obtains a porous carbon support anode material with a rich closed-pore structure, good morphology, low Na nucleation potential, and excellent electrochemical performance through a high-temperature carbonization reaction. This effectively suppresses sodium dendrite formation in carbon-based materials due to excessively high local current, alleviates volume expansion, and solves problems such as a small number of sodium-affinity sites and poor cycle stability, effectively further improving the safety performance of porous carbon materials applied to sodium metal batteries.

[0009] The technical solution of this invention is implemented as follows:

[0010] A method for preparing a carbon support material that alleviates sodium dendrite growth and is rich in micropores and has a closed-pore structure includes the following steps:

[0011] SO1. Phenolic source and cross-linking catalyst are prepared into an aqueous solution, and then formaldehyde solution (analytical grade) is added to carry out the cross-linking reaction. After the reaction is completed, the product is freeze-dried to obtain a sample of rich closed-pore carbon precursor.

[0012] SO2, the precursor sample in step S01 is subjected to a high-temperature carbonization reaction, and after the reaction is completed, it is cooled to room temperature to obtain a sample containing impurities;

[0013] SO3. The sample containing impurities from step S02 is added to the solvent for soaking. After soaking, it is filtered, the filter residue is washed, the filter residue is taken and dried to obtain a carbon support material that alleviates sodium dendrite growth and is rich in micropores and closed-pore structure.

[0014] In a preferred embodiment, in step SO1...

[0015] The phenol source is an organic compound containing a phenolic group; wherein, the organic compound containing a phenolic group is preferably one of 3,5-dihydroxybenzoic acid, resorcinol, or phenol; more preferably, the organic compound containing a phenolic group is 3,5-dihydroxybenzoic acid with a carboxyl group (-COOH).

[0016] The crosslinking catalyst is sodium hydroxide.

[0017] The amount of the phenol source is 10 mmol; the amount of the crosslinking catalyst is 1 g to 2.5 g; and the amount of the aqueous solution is 15-18 ml. More preferably, the amount of the crosslinking catalyst is 1.6 g.

[0018] The crosslinking reaction is carried out at a temperature of 80°C for 3–6 hours. More preferably, the crosslinking reaction is conducted with stirring.

[0019] The freeze-drying time is 12 hours of freezing followed by 12 hours of drying. That is, 12 hours of freezing and 12 hours of drying.

[0020] The freezing method involves transferring the obtained product to a refrigerator for rapid freezing after the reaction is completed; the drying method involves using a freeze dryer for drying.

[0021] The crosslinking reaction is carried out in a reaction flask; more preferably, the reaction flask is a three-necked flask, and the three-necked flask retains a condenser.

[0022] The heating of the crosslinking reaction is carried out in a heating and stirring device, preferably an oil bath device.

[0023] In step SO1, the organic compound containing the phenol source is mixed with the crosslinking catalyst in an aqueous solution, the resulting aqueous solution is transferred to a reaction flask, and then formaldehyde solution (analytical grade) is added and stirred until homogeneous.

[0024] In a preferred embodiment, in step SO2...

[0025] The initial temperature of the high-temperature carbonization reaction is 20℃~40℃, and the reaction temperature is 1700-1900℃. The heating rate is as follows: 15℃ / min in the temperature range of 0-1000℃; 10℃ / min in the temperature range of 1000℃-1600℃; and 7℃ / min in the temperature range of 1600℃-1900℃. The reaction time of the high-temperature carbonization reaction is 60 min.

[0026] The high-temperature carbonization reaction is carried out in a high-vacuum atmosphere.

[0027] The high-temperature carbonization reaction is carried out in a high-temperature calcination apparatus; more preferably, the high-temperature calcination apparatus is a high-vacuum atmosphere sintering furnace.

[0028] The cooling is carried out in a water chiller, which rapidly cools the sample to room temperature using water cooling.

[0029] In a preferred embodiment, in step SO3...

[0030] The solvent is deionized water; the amount of solvent used is 400ml to 500ml. More preferably, soaking and stirring in the solvent can remove residual impurities generated during the reaction.

[0031] The soaking time is 8 to 12 hours. The soaking is carried out in a beaker.

[0032] The filtration is performed 2 to 3 times.

[0033] The washing process employs an alcohol solution; the amount of the alcohol solution used is 30 ml to 50 ml. The alcohol solution is ethanol.

[0034] The drying temperature is 60℃~80℃, and the drying time is 12h~16h. The drying is preferably carried out in an electrically heated forced-air drying oven.

[0035] The preparation method of this invention uses low-cost phenolic resin as raw material to obtain a porous carbon support anode material with rich closed-pore structure, good morphology, low Na nucleation potential and excellent electrochemical performance through high-temperature carbonization reaction. It can effectively suppress sodium dendrites generated by excessive local current in carbon-based materials, alleviate volume expansion, solve problems such as the small number of sodium-loving sites and poor cycle stability, and effectively further improve the safety performance of porous carbon materials applied to sodium metal batteries.

[0036] A carbon support material that alleviates sodium dendrite growth and is rich in micropores and has a closed-pore structure is obtained by the above preparation method.

[0037] The aforementioned carbon support materials that alleviate sodium dendrite growth and are rich in micropores and have closed-pore structures are used in sodium metal batteries.

[0038] Compared with the prior art, the present invention has the following technical effects:

[0039] This invention relates to a carbon support material obtained through high-vacuum sintering, which alleviates sodium dendrite growth and is rich in micropores and closed-pore structures. This material possesses macropores, mesopores, micropores, and abundant closed-pore structures, resulting in a stable carbon structure and mitigating volume changes caused by sodium plating / stripping during cycling. Simultaneously, this porous carbon anode material with abundant closed-pore structures utilizes pores as a three-dimensional Na... + The transport channels facilitate the formation of favorable ion migration paths, thereby reducing the local current density of the material and decreasing the likelihood of dendrite formation, thus improving the safety and lifespan of energy storage devices. The porous carbon support material with abundant closed-pore structures prepared in this invention exhibits uniform distribution. The high-temperature carbonization reaction effectively forms closed-pore structures with suitable pore sizes, providing abundant sodium-affinity sites to guide the uniform deposition of sodium metal, overcoming the problem of dendrite formation in carbon-based materials due to insufficient active sites. Furthermore, the prepared carbon support material, which alleviates sodium dendrite growth and is rich in micropores with closed-pore structures, can be applied in sodium metal batteries. The preparation cost of this invention is low, the method is simple, it is environmentally friendly, and it is suitable for large-scale production. Attached Figure Description

[0040] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0041] Figure 1 This is a SEM characterization image of the carbon support anode material prepared in Example 1 of the present invention, which alleviates sodium dendrite growth and is rich in closed-pore structure.

[0042] Figure 2 This is the XRD characterization image of the carbon support anode material prepared in Example 1 that alleviates sodium dendrite growth and is rich in closed-pore structure.

[0043] Figure 3 TEM characterization image of the carbon support anode material prepared in Example 1 that alleviates sodium dendrite growth and is rich in closed-pore structure;

[0044] Figure 4 The nitrogen adsorption-desorption (BET) test results are shown for the carbon support anode material prepared in Example 1 that alleviates sodium dendrite growth and is rich in closed-pore structure.

[0045] Figure 5 X-ray small foot scattering (SAXS) test image of the carbon support anode material with a closed-pore structure that alleviates sodium dendrite growth and is prepared in Example 1 of this invention;

[0046] Figure 6 Thermogravimetric analysis (TGA-DSC) test results of the carbon support anode material prepared in Example 1 that alleviates sodium dendrite growth and is rich in closed-pore structure.

[0047] Figure 7 The image shows the Na nucleation overpotential test of the half-cell assembled with the carbon support anode material prepared in Example 1, which alleviates sodium dendrite growth and is rich in closed-pore structure.

[0048] Figure 8 This is a rate performance test diagram of a half-cell assembled from the carbon carrier anode material prepared in Example 1, which alleviates sodium dendrite growth and is rich in closed-pore structure.

[0049] Figure 9 The symmetric cell assembled from the closed-pore carbon support anode material prepared in Example 1, which mitigates sodium dendrite growth, performs at 1 mA·cm⁻¹. -2 Current density, 1 mAh·cm -2 Cyclic performance test graphs at capacity density;

[0050] Figure 10The deposition of the carbon support anode material prepared in Example 1, which alleviates sodium dendrite growth and is rich in closed-pore structure, is 5 mAh·cm⁻¹. -2 Capacity characterization diagram;

[0051] Figure 11 The anode material prepared in Example 1, which alleviates sodium dendrite growth and is rich in closed-pore carbon support, was prepared at 0.5 mA·cm⁻¹. -2 Optical microscope characterization image after 1 hour of discharge;

[0052] Figure 12 The image shows the XRD characterization of the pseudo-graphite sheet carbon support anode material prepared in Example 2 for mitigating sodium dendrite growth in sodium metal batteries.

[0053] Figure 13 This is a SEM characterization image of the pseudo-graphite sheet carbon support anode material prepared in Example 2 for mitigating sodium dendrite growth in sodium metal batteries.

[0054] Figure 14 This is a TEM characterization image of the pseudo-graphite sheet carbon support anode material prepared in Example 2 for mitigating sodium dendrite growth in sodium metal batteries.

[0055] Figure 15 The image shows the XRD characterization of the macroporous carbon support anode material prepared in Example 3 for mitigating sodium dendrite growth in sodium metal batteries.

[0056] Figure 16 This is a SEM characterization image of the macroporous carbon support anode material used to alleviate sodium dendrite growth in the high-sodium metal battery prepared in Example 3.

[0057] Figure 17 The image shows the XRD characterization of the thick-sheet graphite carbon support anode material prepared in Example 4 for mitigating sodium dendrite growth in sodium metal batteries.

[0058] Figure 18 This is a SEM characterization image of the thick-sheet graphite carbon support anode material prepared in Example 4 for mitigating sodium dendrite growth in sodium metal batteries.

[0059] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0060] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0061] It should be noted that if the embodiments of the present invention involve directional indicators (such as up, down, left, right, front, back, top, bottom, etc.), the directional indicators are only used to explain the relative positional relationship and movement of the components in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indicators will also change accordingly.

[0062] Furthermore, if the embodiments of this invention involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. If the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

[0063] Carbon-based materials are widely used in various aspects of sodium metal batteries. They can serve as a supporting structure for sodium metal anodes and as a substrate, effectively stabilizing sodium metal deposition, improving the surface morphology of the anode, and inhibiting sodium dendrite growth, thereby enhancing battery safety and cycle life. Through the manipulation of carbon-based materials, properties such as high mechanical strength, low mass, high conductivity, large surface area, and good chemical stability can be obtained. Secondly, carbon-based materials are easy to functionalize and structurally tunable. By modifying carbon-based materials, microporous to ultramicroporous structures can be used as sodium-affinity sites to reduce nucleation overpotential, homogenize the sodium deposition process, and carbon-structured materials often have a high specific surface area, which can reduce local effective current density and delay sodium dendrite growth. Furthermore, the carbon framework structure has good mechanical properties, effectively buffering the volume changes and structural damage caused by sodium metal deposition / stripping. Based on these advantages, carbon-based materials are one of the outstanding candidate materials for use as current collectors in sodium metal anodes.

[0064] By further optimizing porous carbon materials to derive abundant closed-pore structures through high-temperature processing, this microporous, closed-pore carbon-supported anode material was used in sodium metal batteries. It exhibited characteristics such as mitigating sodium dendrite growth, excellent rate performance, and high energy density. This was mainly achieved by utilizing the abundant and appropriately sized closed-pore structures within the material as sodium-affinity sites to induce uniform sodium deposition, thereby mitigating sodium dendrite growth. Furthermore, different closed-pore sizes have varying effects on sodium... + The adsorption energies also vary, so it is very necessary to study a carbon-based material with abundant micropores, closed-pore structure and adjustable pore size for use in sodium-metal batteries.

[0065] The morphology of carbon-based materials for sodium metal batteries is mainly electrospun strips, chemically synthesized blocks, spheres, or sheets. At a more microscopic level, some of these morphologies exhibit porous structures resulting from the raw materials or reaction processes. The microscopic morphology of most porous carbon anode materials in sodium metal batteries is predominantly mesoporous with micropores. Mesopores are suitable as defect donors for Na+. + The inclined region serves as an adsorption site; microporous materials can also act as defects, providing Na... + Pore ​​filling occurs at low potentials, effectively improving the battery's capacity at low voltage plateaus. However, both mesopores and micropores are open pores, serving only as defects to improve certain cycle stability, but their impact on Na+ is limited. + The nucleophilicity of sodium is limited. Besides open pores, abundant closed-pore structures can effectively increase the material's insufficient sodium affinity when only open pores are present. Furthermore, in sodium metal batteries, closed pores act as sodium-affinity sites to induce uniform sodium deposition, resulting in sodium metal batteries with no dendrite growth, excellent rate performance, and high energy density. Therefore, this invention aims to further optimize porous carbon materials to generate abundant closed-pore structures, ensuring uniform sodium deposition at the negative electrode to suppress sodium dendrite growth. Simultaneously, different closed-pore diameters affect the nucleophilicity of sodium. + The adsorption energies also vary, so it is very necessary to study a carbon-based material with abundant closed-pore structure and adjustable pore size for use in sodium-metal batteries.

[0066] The carbon support material prepared by this invention, which is rich in micropores and closed-pore structures and can be used in sodium metal batteries to alleviate sodium dendrite growth, not only effectively increases the closed-pore structure as sodium-loving sites, thereby inducing sodium metal to be uniformly deposited on one side of the carbon-based anode material, which is beneficial to suppressing sodium dendrite growth, stabilizing the carbon skeleton and being able to withstand volume changes during repeated charge and discharge, but also provides more options for ion diffusion paths in three-dimensional open micropore structure, which is beneficial to improving rate performance and long-term stability.

[0067] To achieve the above objectives, in one aspect, embodiments of the present invention provide a method for preparing a carbon support material with a microporous, closed-pore structure that alleviates sodium dendrite growth, comprising the following steps:

[0068] SO1. Phenolic source and cross-linking catalyst are prepared into an aqueous solution, and then formaldehyde solution (analytical grade) is added to carry out the cross-linking reaction. After the reaction is completed, the product is freeze-dried to obtain a sample of rich closed-pore carbon precursor.

[0069] SO2, the precursor sample in step S01 is subjected to a high-temperature carbonization reaction, and after the reaction is completed, it is cooled to room temperature to obtain a sample containing impurities;

[0070] SO3. The sample containing impurities from step S02 is added to the solvent for soaking. After soaking, it is filtered, the filter residue is washed, the filter residue is taken and dried to obtain a carbon support material that alleviates sodium dendrite growth and is rich in micropores and closed-pore structure.

[0071] In a preferred embodiment, in step SO1...

[0072] The phenol source is an organic compound containing a phenolic group; wherein, the organic compound containing a phenolic group is preferably one of 3,5-dihydroxybenzoic acid, resorcinol, or phenol; more preferably, the organic compound containing a phenolic group is 3,5-dihydroxybenzoic acid with a carboxyl group (-COOH).

[0073] The crosslinking catalyst is sodium hydroxide.

[0074] The amount of the phenol source is 10 mmol; the amount of the crosslinking catalyst is 1 g to 2.5 g; and the amount of the aqueous solution is 15-18 ml. More preferably, the amount of the crosslinking catalyst is 1.6 g.

[0075] The crosslinking reaction is carried out at a temperature of 80°C for 3–6 hours. More preferably, the crosslinking reaction is conducted with stirring.

[0076] The freeze-drying time is 12 hours of freezing followed by 12 hours of drying. That is, 12 hours of freezing and 12 hours of drying.

[0077] The freezing method involves transferring the obtained product to a refrigerator for rapid freezing after the reaction is completed; the drying method involves using a freeze dryer for drying.

[0078] The crosslinking reaction is carried out in a reaction flask; more preferably, the reaction flask is a three-necked flask, and the three-necked flask retains a condenser.

[0079] The heating of the crosslinking reaction is carried out in a heating and stirring device, preferably an oil bath device.

[0080] In step SO1, the organic compound containing the phenol source is mixed with the crosslinking catalyst in an aqueous solution, the resulting aqueous solution is transferred to a reaction flask, and then formaldehyde solution (analytical grade) is added and stirred until homogeneous.

[0081] In a preferred embodiment, in step SO2...

[0082] The initial temperature of the high-temperature carbonization reaction is 20℃~40℃, and the reaction temperature is 1700-1900℃. The heating rate is as follows: 15℃ / min in the temperature range of 0-1000℃; 10℃ / min in the temperature range of 1000℃-1600℃; and 7℃ / min in the temperature range of 1600℃-1900℃. The reaction time of the high-temperature carbonization reaction is 60 min.

[0083] The high-temperature carbonization reaction is carried out in a high-vacuum atmosphere.

[0084] The high-temperature carbonization reaction is carried out in a high-temperature calcination apparatus; more preferably, the high-temperature calcination apparatus is a high-vacuum atmosphere sintering furnace.

[0085] The cooling is carried out in a water chiller, which rapidly cools the sample to room temperature using water cooling.

[0086] In a preferred embodiment, in step SO3...

[0087] The solvent is deionized water; the amount of solvent used is 400ml to 500ml. More preferably, soaking and stirring in the solvent can remove residual impurities generated during the reaction.

[0088] The soaking time is 8 to 12 hours. The soaking is carried out in a beaker.

[0089] The filtration is performed 2 to 3 times.

[0090] The washing process employs an alcohol solution; the amount of the alcohol solution used is 30 ml to 50 ml. The alcohol solution is ethanol.

[0091] The drying temperature is 60℃~80℃, and the drying time is 12h~16h. The drying is preferably carried out in an electrically heated forced-air drying oven.

[0092] A carbon support material that alleviates sodium dendrite growth and is rich in micropores and has a closed-pore structure is obtained by the above preparation method.

[0093] The aforementioned carbon support materials that alleviate sodium dendrite growth and are rich in micropores and have closed-pore structures are used in sodium metal batteries.

[0094] Example 1

[0095] A method for preparing a carbon support material with a microporous, closed-pore structure that can alleviate sodium dendrite growth in sodium metal batteries includes the following steps:

[0096] SO1. 10 mmol of 3,5-dihydroxybenzoic acid (phenol source) and 1.6 g of sodium hydroxide (crosslinking catalyst) were dissolved in water and poured into a three-necked flask (with one condenser). The flask was then placed in an oil bath, and 1.6 ml of formaldehyde solution (analytical grade) was added to initiate the crosslinking reaction. The reaction temperature was 80°C, and the reaction time was 5 h. After the reaction, the product was poured out and subjected to freezing for 12 h and drying for 12 h to obtain a sample rich in closed-pore carbon precursors. The freezing method involved transferring the product to a freezer for rapid freezing after the reaction; the drying method involved using a freeze dryer.

[0097] SO2. The precursor sample from step S01 is taken out and placed in a high-vacuum atmosphere sintering furnace for high-temperature carbonization reaction. The initial temperature of the high-temperature carbonization reaction is 20℃~40℃, the reaction temperature is 1800℃, the heating rate is 15℃ / min (0-1000℃), 10℃ / min (1000℃-1600℃), and 7℃ / min (1600℃-1800℃), and the reaction time is 60min. After the reaction is completed, the sample is cooled to room temperature and taken out of the crucible to obtain a sample containing impurities. The cooling method is to use a water chiller and set a cooling program to quickly cool the sample to room temperature by water cooling.

[0098] SO3. Add the sample containing impurities from step S02 to 400ml of deionized water in a beaker and soak and stir for 10h. After soaking, filter twice, wash the filter residue with 30ml of ethanol solution, take the filter residue, and dry it in an electric heating drying oven at 60℃ for 12h to obtain a carbon support material that alleviates sodium dendrite growth and is rich in micropores and closed-pore structure.

[0099] Using the high-performance carbon support material prepared in Example 1 that alleviates sodium dendrite growth and is rich in micropores and closed-pore structures (referred to as the sodium dendrite growth-alleviating and closed-pore structure-rich carbon support anode material) as the active material, the active material, conductive agent, and binder were weighed according to a mass ratio of active material: conductive agent: binder = 6:3:1 and ground and mixed evenly in a mortar. NMP solution (N-methylpyrrolidone) was added and mixed evenly to form a paste. This paste was then coated onto conductive copper foil. The copper foil containing the active material, dried at 80°C for 12 hours, was used as the anode, and the sodium sheet as the counter electrode. A 1 mol / L solution was prepared using sodium hexafluorophosphate (NaPF6) as the solute and dimethyl ether (DME) as the solvent. -1 The solution was used as the electrolyte; finally, 2032 coin-type sodium metal half-cells were assembled and charge-discharge tests were conducted. The charging test cutoff voltage was 0.1V, and the discharge test times were 2h, 1h, 0.5h, 0.33h, and 0.2h, decreasing with increasing current density, maintaining a capacity of 1mAh·cm³. -2Assemble 2032 coin-type sodium metal symmetric cells and conduct cycle stability tests.

[0100] Figure 1 This is a SEM characterization image of the carbon support anode material prepared in Example 1 of this invention, which alleviates sodium dendrite growth and is rich in closed-pore structures. Figure 1 It can be observed that the front side of the hierarchical porous carbon support anode material is a uniformly grown porous structure.

[0101] Figure 2 The XRD characterization image of the carbon support anode material prepared in Example 1, which alleviates sodium dendrite growth and is rich in closed-pore structure, is shown below. Figure 2 It can be observed that the structure of this material consists of two amorphous carbon peaks and a graphite-like peak appearing at 25.9°.

[0102] Figure 3 These are TEM characterization images of the carbon-supported anode material prepared in Example 1, which alleviates sodium dendrite growth and is rich in closed-pore structures. Figure 3 It can be seen that this material is a porous carbon material with uniformly distributed closed pores.

[0103] Figure 4 The BET test image is for the carbon support anode material prepared in Example 1 that alleviates sodium dendrite growth and is rich in closed-pore structure. Figure 4 It can be seen that the material has a microporous structure.

[0104] Figure 5 This is an X-ray small foot scattering (SAXS) pattern of the carbon-supported anode material with reduced sodium dendrite growth and rich in closed-pore structure prepared in Example 1. Figure 5 It can be seen that the material has a scattering vector of The material exhibits a distinct wide hump and has a rich closed-cell structure.

[0105] Figure 6 This is a thermogravimetric analysis (TGA-DSC) chart of the carbon support anode material prepared in Example 1, which alleviates sodium dendrite growth and is rich in closed-pore structures. Figure 6 It can be seen that the material has a high carbon residue rate, and no peaks appeared in the subsequent DSC, forming a stable carbon skeleton.

[0106] Figure 7 This is a test diagram of the Na nucleation overpotential of a half-cell assembled from the carbon support anode material prepared in Example 1, which alleviates sodium dendrite growth and is rich in closed-pore structure. Figure 7 It can be seen that the hierarchical porous carbon support anode material has a high affinity for sodium, with a nucleation overpotential of only 12.7 mV.

[0107] Figure 8This is a rate performance test chart of a half-cell assembled from the carbon support anode material prepared in Example 1, which mitigates sodium dendrite growth and is rich in closed-pore structures. Figure 8 It can be seen that the current density is at 0.5 mA·cm -2 ~5mA·cm -2 The stepwise increase occurs within the range, with the electrode at 0.5, 1, 2, 3, and 5 mA·cm. -2 The average Coulomb efficiency (CE%) is 99.73%, maintaining stable charge and discharge efficiency and exhibiting good rate performance.

[0108] Figure 9 The symmetric cell assembled from the closed-pore carbon support anode material prepared in Example 1, which mitigates sodium dendrite growth, performs at 1 mA·cm⁻¹. -2 Current density, 1 mAh·cm -2 Cyclic performance test graphs at capacity density, from Figure 9 As can be seen, at 1mA·cm -2 After 1500 hours of cycling at a current density, it still maintains a low polarization voltage of 9.2mV, demonstrating good cycling stability.

[0109] Figure 10 The deposition of the carbon support anode material prepared in Example 1, which alleviates sodium dendrite growth and is rich in closed-pore structure, is 5 mAh·cm⁻¹. -2 Capacity characterization diagram, from Figure 10 It can be seen that the material exhibits a small volume change after the deposition of a large amount of Na metal, and the carbon skeleton shows good mechanical properties.

[0110] Figure 11 The anode material prepared in Example 1, which alleviates sodium dendrite growth and is rich in closed-pore carbon support, was prepared at 0.5 mA·cm⁻¹. -2 Optical microscope characterization image one hour after discharge, from Figure 11 It can be seen that this material can guide the uniform deposition of Na metal without obvious dendrite growth.

[0111] Example 2

[0112] A method for preparing a pseudo-graphite sheet carbon support material with a microporous, closed-pore structure that can alleviate sodium dendrite growth in sodium metal batteries includes the following steps:

[0113] SO1. 10 mmol of 3,5-dihydroxybenzoic acid (phenol source) and 2.5 g of sodium hydroxide (crosslinking catalyst) were dissolved in water and poured into a three-necked flask (with one condenser). The flask was then placed in an oil bath, and 1.6 ml of formaldehyde solution (analytical grade) was added to carry out the crosslinking reaction. The crosslinking reaction temperature was 80 °C, and the reaction time was 3 h. After the reaction, the product was poured out and subjected to freezing for 12 h and drying for 12 h to obtain a sample rich in closed-pore carbon precursors. The freezing method was to transfer the product to a refrigerator for rapid freezing after the reaction; the drying method was to use a freeze dryer.

[0114] SO2. The precursor sample from step S01 is taken out and placed in a high-vacuum atmosphere sintering furnace for high-temperature carbonization reaction. The initial temperature of the high-temperature carbonization reaction is 20℃~40℃, the reaction temperature is 1800℃, the heating rate is 15℃ / min (0-1000℃), 10℃ / min (1000℃-1600℃), and 7℃ / min (1600℃-1800℃), and the reaction time is 60min. After the reaction is completed, the sample is cooled to room temperature and taken out of the crucible to obtain a sample containing impurities. The cooling method is to use a water chiller and set a cooling program to quickly cool the sample to room temperature by water cooling.

[0115] SO3. The sample containing impurities from step S02 is added to 500ml of deionized water and soaked in a beaker for 10h with stirring. After soaking, it is filtered twice, and the filter residue is washed with 30ml of ethanol solution. The filter residue is then dried in an electric heating drying oven at 80℃ for 16h to obtain a pseudo-graphite sheet carbon support material that alleviates sodium dendrite growth and is rich in micropores and closed-pore structures (referred to as pseudo-graphite sheet carbon support anode material that alleviates sodium dendrite growth).

[0116] Figure 12 The XRD characterization image shows the pseudo-graphite sheet carbon support anode material prepared in Example 2 for mitigating sodium dendrite growth in sodium metal batteries. Figure 12 It can be observed that the structure of this material consists of two amorphous carbon peaks and a graphite spike appearing at 25.9°, and the carbon (002) peaks are more concentrated than those of the carbon peaks. Figure 2 The (002) carbon peak of the graded porous carbon support anode material is narrower and sharper.

[0117] Figure 13 This is a SEM characterization image of the pseudo-graphite sheet carbon support anode material prepared in Example 2 for mitigating sodium dendrite growth in sodium metal batteries. Figure 13 It can be seen that the material is predominantly sheet-like, with sheets stacked on top of each other, and the sheets have a small number of pores on their walls.

[0118] Figure 14 These are TEM characterization images of the pseudo-graphite sheet carbon support anode material prepared in Example 2 for mitigating sodium dendrite growth in sodium metal batteries. Figure 14 It can be seen that the carbon atoms in this material are arranged in an orderly manner, the number of carbon layers is high, the interlayer spacing is small, and the degree of graphitization is high.

[0119] Example 3

[0120] A method for preparing a macroporous carbon support material with a microporous and closed-pore structure that can alleviate sodium dendrite growth in sodium metal batteries includes the following steps:

[0121] SO1. 10 mmol of 3,5-dihydroxybenzoic acid (phenol source) and 1 g of sodium hydroxide (crosslinking catalyst) were prepared into an aqueous solution and poured into a three-necked flask (with one condenser). The flask was then placed in an oil bath, and 1.6 ml of formaldehyde solution (analytical grade) was added to carry out the crosslinking reaction. The crosslinking reaction temperature was 80°C, and the reaction time was 6 h. After the reaction, the product was poured out and subjected to freezing for 12 h and drying for 12 h to obtain a sample rich in closed-pore carbon precursors. The freezing method was to transfer the product to a refrigerator for rapid freezing after the reaction; the drying method was to use a freeze dryer.

[0122] SO2. The precursor sample from step S01 is taken out and placed in a high-vacuum atmosphere sintering furnace for high-temperature carbonization reaction. The initial temperature of the high-temperature carbonization reaction is 20℃~40℃, the reaction temperature is 1800℃, the heating rate is 15℃ / min (0-1000℃), 10℃ / min (1000℃-1600℃), and 7℃ / min (1600℃-1800℃), and the reaction time is 60min. After the reaction is completed, the sample is cooled to room temperature and taken out of the crucible to obtain a sample containing impurities. The cooling method is to use a water chiller and set a cooling program to quickly cool the sample to room temperature by water cooling.

[0123] SO3. The sample containing impurities from step S02 is added to 500ml of deionized water and soaked in a beaker for 10h with stirring. After soaking, it is filtered twice, and the filter residue is washed with 30ml of ethanol solution. The filter residue is then dried in an electric heating drying oven at 60℃ for 16h to obtain a macroporous carbon support material that alleviates sodium dendrite growth and is rich in micropores and closed-pore structures (hereinafter referred to as macroporous carbon support anode material that alleviates sodium dendrite growth).

[0124] Figure 15 The XRD characterization image shows the macroporous carbon support anode material prepared in Example 3 for mitigating sodium dendrite growth in sodium metal batteries. Figure 15It can be observed that the structure of this material consists of two amorphous carbon peaks.

[0125] Figure 16 This is a SEM characterization image of the macroporous carbon support anode material used to alleviate sodium dendrite growth in the high-sodium metal battery prepared in Example 3. Figure 16 It can be seen that the material is predominantly a dispersed block, with a large number of macropores on the block material and only a small number of hierarchical pores with smaller diameters on the walls of the pores.

[0126] Example 4

[0127] A method for preparing a thick sheet-like graphitic carbon support material with a microporous, closed-pore structure that can alleviate sodium dendrite growth in sodium metal batteries includes the following steps:

[0128] SO1. 10 mmol of resorcinol (phenol source) and 1.6 g of sodium hydroxide (crosslinking catalyst) were dissolved in water and poured into a three-necked flask (with one condenser). The flask was then placed in an oil bath, and 1.6 ml of formaldehyde solution (analytical grade) was added to carry out the crosslinking reaction. The crosslinking reaction temperature was 80 °C, and the reaction time was 6 h. After the reaction, the product was poured out and subjected to freezing for 12 h and drying for 12 h to obtain a sample rich in closed-pore carbon precursors. The freezing method was to transfer the product to a refrigerator for rapid freezing after the reaction; the drying method was to use a freeze dryer.

[0129] SO2. The precursor sample from step S01 is taken out and placed in a high-vacuum atmosphere sintering furnace for high-temperature carbonization reaction. The initial temperature of the high-temperature carbonization reaction is 20℃~40℃, the reaction temperature is 1800℃, the heating rate is 15℃ / min (0-1000℃), 10℃ / min (1000℃-1600℃), and 7℃ / min (1600℃-1800℃), and the reaction time is 60min. After the reaction is completed, the sample is cooled to room temperature and taken out of the crucible to obtain a sample containing impurities. The cooling method is to use a water chiller and set a cooling program to quickly cool the sample to room temperature by water cooling.

[0130] SO3. The sample containing impurities from step S02 is added to 500ml of deionized water and soaked in a beaker for 10h with stirring. After soaking, it is filtered twice, and the filter residue is washed with 30ml of ethanol solution. The filter residue is then dried in an electric heating drying oven at 60℃ for 16h to obtain a thick sheet graphite carbon support material that alleviates sodium dendrite growth and is rich in micropores and closed-pore structures (referred to as thick sheet graphite carbon support anode material that alleviates sodium dendrite growth).

[0131] Figure 17The XRD characterization image shows the thick-sheet graphite carbon support anode material prepared in Example 4 for mitigating sodium dendrite growth in sodium metal batteries. Figure 17 It can be observed that the structure of this material consists of two amorphous carbon peaks.

[0132] Figure 18 This is a SEM characterization image of the thick-sheet graphite carbon support anode material prepared in Example 4 for mitigating sodium dendrite growth in sodium metal batteries. Figure 18 It can be seen that the material is a relatively thick sheet, and almost no obvious pore structure can be observed on the sheet.

[0133] Comparative Example 1

[0134] Reference for this comparative example: L. Guo, C. Qiu, H. Song, et al. Boosting Molecular Cross-Linking in a Phenolic Resin for Spherical Hard Carbon with Enriched ClosedPores toward Enhanced Sodium Storage Ability. ACS Applied Materials & Interfaces 2024 16(21), 27419-27428. A method for preparing spherical carbon anode materials with abundant closed pores, the specific steps are as follows:

[0135] (1) Resorcinol and benzaldehyde were added to a three-necked flask at a molar ratio of 1:2. Then, 80 mL of deionized water and 1 M ammonia (wt = 25%) were added, and the solution was stirred using a stirrer. The mixture was heated to 80 °C and maintained for 2 hours to obtain solution A;

[0136] (2) The obtained solution A was poured into a PTFE-lined high-pressure autoclave reactor for a high-temperature and high-pressure hydrothermal reaction at a reaction temperature of 150°C and a reaction time of 6 hours to obtain solution B.

[0137] (3) Centrifuge the suspension of solution B to obtain PF precipitate, then wash it three times each with deionized water and ethanol, and finally dry the powder in an oven at 80℃ for 12h to obtain PF powder.

[0138] (4) The PF powder was placed in a tube furnace and heated to 1500°C in an Ar atmosphere at a heating rate of 2°C / min. The temperature was held for 2 hours to obtain a spherical carbon anode material with abundant closed pores.

[0139] A comparison is made between the method of this invention and Comparative Example 1: The synthesis steps of Comparative Example 1 are cumbersome, requiring hydrothermal reaction pretreatment followed by high-temperature carbonization, which takes a long time to obtain closed-pore carbon materials. Furthermore, the resulting material is spherical hard carbon, lacking a three-dimensional porous structure as an effective channel for ion transport, thus limiting its application in energy storage devices for rapid charge-discharge and increased storage capacity. In contrast, the method of this invention can provide oxygen-containing functional groups on the phenolic source material without the need for hydrothermal pretreatment, resulting in a shorter synthesis time and lower energy consumption. It can be used for the rapid preparation of high-performance graded porous carbon carrier anode materials for sodium metal batteries, exhibiting greater versatility.

[0140] Comparative Example 2

[0141] References for this comparative example: J Lin, Q Zhou, X Xiong, et al. Steric Hindrance Engineering to Modulate the Closed Pores Formation of Polymer-Derived HardCarbon for High-Performance Sodium-Ion Batteries. Angew. Chem. Int. Ed. 2024, 63, e202409906. A method for adjusting polymer-derived carbon anode materials by steric hindrance, the specific steps of which are as follows:

[0142] (1) Disperse 2g of resorcinol in a three-necked round-bottom flask containing 15mL of anhydrous ethanol, then add 1mol / L NaOH solution as a catalyst, and then stir continuously to form a homogeneous solution.

[0143] (2) The solution was placed in an oil bath with a glass air condenser and heated to 60°C. Then, cinnamaldehyde was added dropwise to the solution at a molar ratio of resorcinol to cinnamaldehyde of 1:1.25. The mixture was stirred and reacted for 4 hours.

[0144] (3) After transferring the resulting mixture to a beaker, remove most of the ethanol in a fume hood at room temperature;

[0145] (4) The residue was cured at 180°C for 2 hours, ground into precursor powder, washed and filtered three times with deionized water, and dried at 80°C overnight to obtain RFSH.

[0146] (5) The dried RFSH was heated to 1400℃ in a tube furnace under Ar atmosphere at a heating rate of 2℃ / min and carbonized for 1 hour to obtain RFSH-1400, a hydrocarbon compound with a closed-cell structure derived from the polymer.

[0147] A comparison was made between the method of this invention and Comparative Example 2: the synthesis steps of Comparative Example 2 were cumbersome, requiring solvent removal and curing treatment. However, the method of this invention no longer uses thermal curing to assist in the formation of a stable framework. Instead, the precursor is directly carbonized to synthesize a three-dimensional porous structure, enriching the microporous and closed-pore carbon structure. Furthermore, the solvent and catalyst, acting as templates, can optimize the morphology during the reaction, forming a hierarchical porous structure with macropores, mesopores, micropores, and abundant closed pores. By selecting appropriate reactant ratios, the over-graphitization of carbon materials is suppressed while simultaneously achieving suitable closed pore sizes, improving the stability of the carbon framework and effectively simplifying the steps for preparing high-performance hierarchical porous carbon support anode materials for sodium metal batteries with abundant closed-pore structures.

[0148] Compared with the prior art, the present invention has the following technical effects:

[0149] This invention relates to a carbon support material obtained through high-vacuum sintering, which alleviates sodium dendrite growth and is rich in micropores and closed-pore structures. This material possesses macropores, mesopores, micropores, and abundant closed-pore structures, resulting in a stable carbon structure and mitigating volume changes caused by sodium plating / stripping during cycling. Simultaneously, this porous carbon anode material with abundant closed-pore structures utilizes pores as a three-dimensional Na... + The transport channels facilitate the formation of favorable ion migration paths, thereby reducing the local current density of the material and decreasing the likelihood of dendrite formation, thus improving the safety and lifespan of energy storage devices. The porous carbon support material with abundant closed-pore structures prepared in this invention exhibits uniform distribution. The high-temperature carbonization reaction effectively forms closed-pore structures with suitable pore sizes, providing abundant sodium-affinity sites to guide the uniform deposition of sodium metal, overcoming the problem of dendrite formation in carbon-based materials due to insufficient active sites. Furthermore, the prepared carbon support material, which alleviates sodium dendrite growth and is rich in micropores with closed-pore structures, can be applied in sodium metal batteries. The preparation cost of this invention is low, the method is simple, it is environmentally friendly, and it is suitable for large-scale production.

[0150] The above description is merely a preferred embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural transformations made using the contents of the present invention under the inventive concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. A method for preparing a carbon support material with microporous, closed-pore structure that alleviates sodium dendrite growth, characterized in that: Includes the following steps: S01. Prepare an aqueous solution of phenol source and cross-linking catalyst, then add formaldehyde solution to carry out cross-linking reaction. After the reaction is completed, freeze-dry the product to obtain a rich closed-pore carbon precursor sample. S02. The precursor sample from step S01 is subjected to a high-temperature carbonization reaction. After the reaction is completed, it is cooled to room temperature to obtain a sample containing impurities. S03. The sample containing impurities from step S02 is soaked in solvent; after soaking, it is filtered, the filter residue is washed, the filter residue is taken and dried to obtain a carbon support material that alleviates sodium dendrite growth and is rich in micropores and closed-pore structures; In step S01, the phenol source is an organic compound containing a phenolic group; the organic compound containing a phenolic group is 3,5-dihydroxybenzoic acid. The crosslinking catalyst is sodium hydroxide; The amount of the phenol source is 10 mmol; the amount of the crosslinking catalyst added is 1g to 2.5g; the amount of the aqueous solution is 15-18ml; The crosslinking reaction is carried out at a temperature of 80°C for 3–6 hours. The freeze-drying time is 12 hours of freezing followed by 12 hours of drying. In step S02, the initial temperature of the high-temperature carbonization reaction is 20℃~40℃, the reaction temperature is 1700-1900℃, and the heating rate is: 15℃ / min in the temperature range of 0-1000℃; 10℃ / min in the temperature range of 1000℃-1600℃; and 7℃ / min in the temperature range of 1600℃-1900℃. The reaction time of the high-temperature carbonization reaction is 60 min.

2. The method for preparing a carbon support material with microporous and closed-pore structure that alleviates sodium dendrite growth according to claim 1, characterized in that: In step S01, The freezing method involves transferring the obtained product to a refrigerator for rapid freezing after the reaction is complete; the drying method involves using a freeze dryer. The heating of the crosslinking reaction is carried out in a heating and stirring device, which is an oil bath device.

3. The method for preparing a carbon support material with microporous and closed-pore structure that alleviates sodium dendrite growth according to claim 1, characterized in that: In step S02, The high-temperature carbonization reaction is carried out in a high-vacuum atmosphere; The high-temperature carbonization reaction is carried out in a high-temperature calcination device, which is a high-vacuum atmosphere sintering furnace. The cooling is performed in a water chiller.

4. The method for preparing a carbon support material with microporous and closed-pore structure that alleviates sodium dendrite growth according to claim 1, characterized in that: In step S03, The solvent is deionized water; the amount of solvent used is 400ml to 500ml. The soaking time is 8 to 12 hours; The filtration is performed 2 to 3 times. The washing process employs an alcohol solution; the amount of the alcohol solution used is 30ml to 50ml. The drying temperature is 60℃~80℃, and the drying time is 12h~16h.

5. A carbon support material that alleviates sodium dendrite growth and is rich in micropores and has a closed-pore structure is obtained by the preparation method described in any one of claims 1-4.

6. The carbon support material of claim 5, which alleviates sodium dendrite growth and is rich in micropores and has a closed-pore structure, is used in sodium metal batteries.

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